Halogen free flame retardant thermoplastic elastomer compositions having improved insulation resistance

ABSTRACT

Halogen-free flame retardant compositions comprising copolyetherester thermoplastic elastomers, melamine cyanurate and epoxy-containing compounds and cables and wires made from such flame retardant polymer composition provide good electrical insulation resistance during use.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional application under 35 USC 120 and claims the benefitof U.S. application Ser. No. 13/910,414 filed Jun. 5, 2013 now pending,the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of halogen free flameretardant compositions comprising thermoplastic elastomers and to theiruses in cables and wires.

BACKGROUND OF THE INVENTION

Due to excellent mechanical properties (e.g., elongation at break, tearstrength, tensile strength, flex life, and abrasion resistance),polymeric compositions based on copolyetherester elastomers have beenused in a wide range of applications including manufacture of articlesfor use in the automotive, wire and cable, fluid power,electrical/electronic, hose and tubing, and appliance fields.

In particular, copolyetherester elastomers are used in the manufactureof insulating layers for wire and cable applications in the automotive,building and construction industries. The wire and cable coatingprovides electrical insulation but also imparts mechanical, chemical andphysical protection. Because temperatures in excess of 125° C. are oftenreached in the underhood compartments of automobiles or withinbuildings, temperature specifications for wire and cable insulationmaterials in both dry and humid environment conditions are constantlyincreasing. Further, in these highly demanding applications it isnecessary that the insulation material meet additional requirementsincluding flame retardancy, thermal resistance, hydrolysis resistanceand high elongation.

Polyvinyl chloride (PVC) is the most widely used material for wire andcable insulation. However, in many instances, PVC is perceived as anenvironmental threat. It would be desirable to have an alternativehalogen-free flame retardant thermoplastic material available for use inwire and cable applications that require a flexible material thatexhibits resistance to high temperature and hydrolysis as an alternativewire and cable insulation material.

Various flame retardant systems have been developed and used inpolymeric material, e.g., polyesters, to improve the fire-resistancethereof. However, due to toxicity concerns, halogen-free flameretardants are gaining increased attention. Among the varioushalogen-free flame retardants, phosphorus compounds (such as salts ofphosphinic or diphosphinic acids) are used extensively due to theirstability and flame retardant effectiveness. Prior art has alsodemonstrated that various types of synergistic compounds can be used incombination with the phosphorus compounds to further maximize the flameretardant effectiveness thereof. For example, U.S. Pat. No. 6,547,992discloses the use of synthetic inorganic compounds such as oxygencompounds of silicon, magnesium compounds, metal carbonates of metals ofthe second main group of the periodic table, red phosphorus, zinccompounds, aluminum compounds, or combinations thereof as flameretardant synergists; U.S. Pat. No. 6,716,899 discloses the use oforganic phosphorus-containing compounds as flame retardant synergists;U.S. Pat. No. 6,365,071 discloses the use of nitrogen-containingcompounds (e.g., melamine cyanurate, melamine phosphate, melaminepyrophosphate, or melamine diborate) as flame retardant synergists; andU.S. Pat. No. 6,255,371 discloses the use of reaction products ofphosphoric acids with melamine or condensed product of melamine (e.g.,melamine polyphosphate (MPP)) as flame retardant synergists. Moreover,U.S. Patent Publication No. 2008/0039571 discloses the use of metalhydroxides, antimony compounds, boron compounds, phosphorous compounds(e.g., organic phosphate esters, phosphates, halogenated phosphoruscompounds, inorganic phosphorus containing salts, etc.), or other metalcompounds as primary flame retardants or flame retardant synergists.

Particularly, European Patent Publication No. EP1883081 and PCT PatentPublication Nos. WO2009/047353 and WO2010/094560 each disclose flameretardant elastomeric compositions useful in forming insulating layersand/or jackets of wires and cables. In those disclosures, combinationsof (i) a metal salt of a phosphinic acid and/or a diphosphinic acid,(ii) a nitrogen containing compound (e.g., melamine polyphosphate), and(iii) an inorganic compound (e.g., zinc borate) are taught as preferredflame retardant packages. It has been known in the art that the presenceof high levels of additives, such as flame retardant additives, inpolymer compositions may cause deterioration of certain properties. Itis desirable that such polymer compositions have low flammability, highthermal stability and good electrical insulation properties while stillmaintaining other mechanical properties.

It is an object of the present invention to provide compositions andwires and cables made thereof that exhibit good mechanical performance,good flame retardance and good electrical insulation resistance underdry as well as hot and humid conditions.

SUMMARY OF THE INVENTION

The present invention is directed to flame retardant polymercompositions comprising:

-   -   a) one or more copolyetherester thermoplastic elastomers;    -   b) melamine cyanurate;    -   c) at least one epoxy-containing compound; and    -   d) optionally at least one compound selected from the group        consisting of phosphites. aromatic phosphate ester flame        retardants and mixtures thereof;        -   with the proviso that i) when the flame retardant polymer            composition comprises an aromatic phosphate ester flame            retardant and a phosphite, the amount of epoxy-containing            compound present is such that the total epoxy functional            group equivalent weight is at least about 32            milliequivalents per kg of the combined weight of the one or            more copolyetherester thermoplastic elastomers and the            aromatic phosphate ester flame retardant and ii) when the            flame retardant polymer composition comprises an aromatic            phosphate ester flame retardant in the absence of phosphite,            the amount of epoxy-containing compound present is such that            the total epoxy functional group equivalent weight is at            least about 56 milliequivalents per kg of the combined            weight of the one or more copolyetherester thermoplastic            elastomers and the aromatic phosphate ester flame retardant.

In a preferred embodiment, the flame retardant polymer compositionconsists of:

-   -   a) one or more copolyetherester thermoplastic elastomers,    -   b) an amount of melamine cyanurate that is at least from at or        equal to 10 weight percent based on the total weight of the        flame retardant polymer composition;    -   c) one or more epoxy compounds; and optionally    -   d) 0 to 2 weight percent based of the total weight of the flame        retardant polymer composition of a phosphite,    -   e) 0 to 15 weight percent based on the total weight of the flame        retardant polymer composition of an aromatic phosphate ester        flame retardant, with the proviso that i) when the flame        retardant polymer composition comprises an aromatic phosphate        ester flame retardant and a phosphite, the amount of        epoxy-containing compound present is such that the total epoxy        functional group equivalent weight is at least about 32        milliequivalents per kg of the combined weight of the one or        more copolyetherester thermoplastic elastomers and the aromatic        phosphate ester flame retardant and ii) when the flame retardant        polymer composition comprises an aromatic phosphate ester flame        retardant in the absence of phosphite, the amount of        epoxy-containing compound present is such that the total epoxy        functional group equivalent weight is at least about 56        milliequivalents per kg of the combined weight of the one or        more copolyetherester thermoplastic elastomers and the aromatic        phosphate ester flame retardant. and    -   f) from 0.05 to 10 weight percent based on the total weight of        the flame retardant polymer composition of additives    -   wherein the sum of components a) to f) amounts to 100 weight        percent.

Preferably, the additives used in the flame retardant polymercompositions of the present invention are selected from the groupconsisting of stabilizers, processing agents, metal deactivators,antioxidants, UV stabilizers, heat stabilizers, dyes and/or pigments.

Preferably, the amount of melamine cyanurate b) present in the flameretardant polymer composition of the present invention is from at orabout 10 to 30 weight percent based on the total weight of the flameretardant polymer composition and the amount of epoxy-containingcompound c) present in the flame retardant polymer composition of thepresent invention is such that it provides from at or about 2.4 to about10 milliequivalents of total epoxy functionality based on hundred gramsof the total weight of the flame retardant polymer composition.

In a preferred embodiment, the flame retardant polymer composition ofthe present invention further comprises phosphites and/or aromaticphosphate esters wherein the amount of phosphite d) is from at or about0.1 to 1 weight percent based on the total weight of the flame retardantpolymer composition and wherein the amount of aromatic phosphate estere) is from at or about 2 to 12 weight percent based on the total weightof the flame retardant polymer composition.

The preferred epoxy-containing compound c) used in the flame retardantpolymer composition of the present invention is selected from the groupconsisting of 2,2-bis(4-hydroxyphenyl)propane-epichlorohydrincopolymers, tetraglycidyl ethers of tetraphenol ethane and combinationsthereof

The preferred phosphite d) used in the flame retardant polymercomposition of the present invention is a pentaerythritol diphosphite.

The preferred aromatic phosphate ester flame retardant e) used in theflame retardant polymer composition of the present invention is selectedfrom the group consisting of resorcinol bis(di-2,6-dimethylphenylphosphate) and bisphenol bis(di-2,6-dimethylphenyl phosphate) andcombination thereof.

Also described herein are wires or cables comprising a coating made ofthe flame retardant polymer compositions of the present invention andthe use of the flame retardant polymer compositions of the presentinvention for making an insulated wire and/or cable.

DETAILED DESCRIPTION OF THE INVENTION

The following definitions are to be used to interpret the meaning of theterms discussed in the description and recited in the claims.

As used herein, the article “a” indicates one as well as more than oneand does not necessarily limit its referent noun to the singular.

As used herein, the terms “about” and “at or about” mean that the amountor value in question may be the value designated or some other valuethat is approximately or about the same. The phrase is intended toconvey that similar values promote equivalent results or effectsaccording to the invention.

The one or more copolyetherester thermoplastic elastomers suitable foruse in the flame retardant compositions described herein are preferablypresent in the compositions of the invention in an amount from at orabout 50 to at or about 80 weight percent, the weight percentage beingbased on the total weight of the flame retardant polymer composition.

Copolyetherester thermoplastic elastomers of the present invention havea multiplicity of recurring long-chain ester units and short-chain esterunits joined head-to-tail through ester linkages, said long-chain esterunits being represented by formula (A):

and said short-chain ester units being represented by formula (B):

whereinG is a divalent radical remaining after the removal of terminal hydroxylgroups from poly(alkylene oxide)glycols having a number averagemolecular weight of between about 400 and about 6000, or preferablybetween about 400 and about 3000;R is a divalent radical remaining after removal of carboxyl groups froma dicarboxylic acid having a molecular weight of less than about 300;D is a divalent radical remaining after removal of hydroxyl groups froma diol having a molecular weight less than about 250.

As used herein, the term “long-chain ester units” as applied to units ina polymer chain refers to the reaction product of a long-chain glycolwith a dicarboxylic acid. Suitable long-chain glycols are poly(alkyleneoxide) glycols having terminal (or as nearly terminal as possible)hydroxy groups and having a number average molecular weight of fromabout 400 to about 6000, and preferably from about 600 to about 3000.Preferred poly(alkylene oxide) glycols include poly(tetramethyleneoxide) glycol, poly(trimethylene oxide) glycol, poly(propylene oxide)glycol, poly(ethylene oxide) glycol, copolymer glycols of these alkyleneoxides, and block copolymers such as ethylene oxide-cappedpoly(propylene oxide) glycol. Mixtures of two or more of these glycolscan be used.

As used herein, the term “short-chain ester units” as applied to unitsin a polymer chain of the copolyetheresters refers to low molecularweight compounds or polymer chain units having molecular weights lessthan about 550. They are made by reacting a low molecular weight diol ora mixture of diols (molecular weight below about 250) with adicarboxylic acid to form ester units represented by Formula (B) above.Included among the low molecular weight diols which react to formshort-chain ester units suitable for use for preparing copolyetherestersare acyclic, alicyclic and aromatic dihydroxy compounds. Preferredcompounds are diols with about 2-15 carbon atoms such as ethylene,propylene, isobutylene, tetramethylene, 1,4-pentamethylene,2,2-dimethyltrimethylene, hexamethylene and decamethylene glycols,dihydroxycyclohexane, cyclohexane dimethanol, resorcinol, hydroquinone,1,5-dihydroxynaphthalene, and the like. Especially preferred diols arealiphatic diols containing 2-8 carbon atoms, and a more preferred diolis 1,4-butanediol. Included among the bisphenols which can be used arebis(p-hydroxy)diphenyl, bis(p-hydroxyphenyl)methane, andbis(p-hydroxyphenyl)propane. Equivalent ester-forming derivatives ofdiols are also useful (e.g., ethylene oxide or ethylene carbonate can beused in place of ethylene glycol or resorcinol diacetate can be used inplace of resorcinol).

As used herein, the term “diols” includes equivalent ester-formingderivatives such as those mentioned. However, any molecular weightrequirements refer to the corresponding diols, not their derivatives.

Dicarboxylic acids that can react with the foregoing long-chain glycolsand low molecular weight diols to produce the copolyetheresters arealiphatic, cycloaliphatic or aromatic dicarboxylic acids of a lowmolecular weight, i.e., having a molecular weight of less than about300. The term “dicarboxylic acids” as used herein includes functionalequivalents of dicarboxylic acids that have two carboxyl functionalgroups that perform substantially like dicarboxylic acids in reactionwith glycols and diols in forming copolyetherester polymers. Theseequivalents include esters and ester-forming derivatives such as acidhalides and anhydrides. The molecular weight requirement pertains to theacid and not to its equivalent ester or ester-forming derivative.

Thus, an ester of a dicarboxylic acid having a molecular weight greaterthan 300 or a functional equivalent of a dicarboxylic acid having amolecular weight greater than 300 are included provided thecorresponding acid has a molecular weight below about 300. Thedicarboxylic acids can contain any substituent groups or combinationsthat do not substantially interfere with copolyetherester polymerformation and use of the copolyetherester polymer in the flame retardantcompositions of the invention.

As used herein, the term “aliphatic dicarboxylic acids” refers tocarboxylic acids having two carboxyl groups each attached to a saturatedcarbon atom. If the carbon atom to which the carboxyl group is attachedis saturated and is in a ring, the acid is cycloaliphatic. Aliphatic orcycloaliphatic acids having conjugated unsaturation often cannot be usedbecause of homopolymerization. However, some unsaturated acids, such asmaleic acid, can be used.

As used herein, the term “aromatic dicarboxylic acids” refer todicarboxylic acids having two carboxyl groups each attached to a carbonatom in a carbocyclic aromatic ring structure. It is not necessary thatboth functional carboxyl groups be attached to the same aromatic ringand where more than one ring is present, they can be joined by aliphaticor aromatic divalent radicals or divalent radicals such as —O— or —SO₂—.Representative useful aliphatic and cycloaliphatic acids that can beused include sebacic acid; 1,3-cyclohexane dicarboxylic acid;1,4-cyclohexane dicarboxylic acid; adipic acid; glutaric acid;4-cyclohexane-1,2-dicarboxylic acid; 2-ethylsuberic acid;cyclopentanedicarboxylic acid, decahydro-1,5-naphthylene dicarboxylicacid; 4,4′-bicyclohexyl dicarboxylic acid; decahydro-2,6-naphthylenedicarboxylic acid; 4,4′-methylenebis(cyclohexyl) carboxylic acid; and3,4-furan dicarboxylic acid. Preferred acids are cyclohexanedicarboxylic acids and adipic acid.

Representative aromatic dicarboxylic acids include phthalic,terephthalic and isophthalic acids; bibenzoic acid; substituteddicarboxy compounds with two benzene nuclei such asbis(p-carboxyphenyl)methane; p-oxy-1,5-naphthalene dicarboxylic acid;2,6-naphthalene dicarboxylic acid; 2,7-naphthalene dicarboxylic acid;4,4′-sulfonyl dibenzoic acid and C1-C12 alkyl and ring substitutionderivatives thereof, such as halo, alkoxy, and aryl derivatives. Hydroxyacids such as p-(beta-hydroxyethoxy)benzoic acid can also be usedprovided an aromatic dicarboxylic acid is also used.

Aromatic dicarboxylic acids are a preferred class for preparing thecopolyetherester elastomers useful for this invention. Among thearomatic acids, those with 8-16 carbon atoms are preferred, particularlyterephthalic acid alone or with a mixture of phthalic and/or isophthalicacids.

The copolyetherester elastomer preferably comprises from at or about 15to at or about 99 weight percent short-chain ester units correspondingto Formula (B) above, the remainder being long-chain ester unitscorresponding to Formula (A) above. More preferably, thecopolyetherester elastomers comprise from at or about 20 to at or about95 weight percent, and even more preferably from at or about 50 to at orabout 90 weight percent short-chain ester units, where the remainder islong-chain ester units. More preferably, at least about 70% of thegroups represented by R in Formulae (A) and (B) above are 1,4-phenyleneradicals and at least about 70% of the groups represented by D inFormula (B) above are 1,4-butylene radicals and the sum of thepercentages of R groups which are not 1,4-phenylene radicals and Dgroups that are not 1,4-butylene radicals does not exceed 30%. If asecond dicarboxylic acid is used to prepare the copolyetherester,isophthalic acid is preferred and if a second low molecular weight diolis used, ethylene glycol, 1,3-propanediol, cyclohexanedimethanol, orhexamethylene glycol are preferred.

A blend or mixture of two or more copolyetherester elastomers can beused. The copolyetherester elastomers used in the blend need not on anindividual basis come within the values disclosed hereinbefore for theelastomers. However, the blend of two or more copolyetheresterelastomers must conform to the values described herein for thecopolyetheresters on a weighted average basis. For example, in a mixturethat contains equal amounts of two copolyetherester elastomers, onecopolyetherester elastomer can contain 60 weight percent short-chainester units and the other resin can contain 30 weight percentshort-chain ester units for a weighted average of 45 weight percentshort-chain ester units.

Preferred copolyetherester elastomers include, but are not limited to,copolyetherester elastomers prepared from monomers comprising (1)poly(tetramethylene oxide) glycol; (2) a dicarboxylic acid selected fromisophthalic acid, terephthalic acid and mixtures thereof; and (3) a diolselected from 1,4-butanediol, 1,3-propanediol and mixtures thereof, orfrom monomers comprising (1) poly(trimethylene oxide) glycol; (2) adicarboxylic acid selected from isophthalic acid, terephthalic acid andmixtures thereof; and (3) a diol selected from 1,4-butanediol,1,3-propanediol and mixtures thereof, or from monomers comprising (1)ethylene oxide-capped poly(propylene oxide) glycol; (2) a dicarboxylicacid selected from isophthalic acid, terephthalic acid and mixturesthereof; and (3) a diol selected from 1,4-butanediol, 1,3-propanedioland mixtures thereof.

Preferably, the copolyetherester elastomers described herein areprepared from esters or mixtures of esters of terephthalic acid and/orisophthalic acid, 1,4-butanediol and poly(tetramethylene ether)glycol orpoly(trimethylene ether) glycol or ethylene oxide-capped polypropyleneoxide glycol, or are prepared from esters of terephthalic acid, e.g.dimethylterephthalate, 1,4-butanediol and poly(ethylene oxide)glycol.More preferably, the copolyetheresters are prepared from esters ofterephthalic acid, e.g. dimethylterephthalate, 1,4-butanediol andpoly(tetramethylene ether)glycol.

In a preferred embodiment, the flame retardant polymer compositionsaccording to the present invention comprise copolyetherester elastomersprepared from monomers comprising (1) poly(tetramethylene oxide) glycolor poly(trimethylene oxide) glycol and mixtures thereof; (2) adicarboxylic acid selected from the group consisting of isophthalicacid, terephthalic acid and mixtures thereof; and (3) a diol selectedfrom the group consisting of 1,4-butanediol, 1,3-propanediol andmixtures thereof.

More preferably, the flame retardant polymer compositions according tothe present invention comprise copolyetherester elastomers prepared frommonomers comprising (1) poly(tetramethylene oxide) glycol; (2) adicarboxylic acid selected from the group consisting of terephthalicacid; and (3) a diol selected from the group consisting of1,4-butanediol, 1,3-propanediol and mixtures thereof and wherein thelevel of poly(tetramethylene oxide) glycol is less than about 25 weightpercent based on the total weight of the copolyetherester elastomers.

In another embodiment, the flame retardant polymer compositionsaccording to the present invention comprise a blend of at least onecopolyetherester elastomer prepared from monomers comprising (1)poly(tetramethylene oxide) glycol; (2) a dicarboxylic acid selected fromthe group consisting of terephthalic acid; and (3) a diol selected fromthe group consisting of 1,4-butanediol, 1,3-propanediol and mixturesthereof and wherein the level of poly(tetramethylene oxide) glycol isless than about 25 weight percent based on the total weight of thecopolyetherester elastomers, and of at least one copolyetheresterthermoplastic elastomer prepared from monomers comprising (1)poly(tetramethylene oxide) glycol; (2) a dicarboxylic acid selected fromthe group consisting of mixtures of isophthalic acid and terephthalicacid; and (3) a diol selected from the group consisting of1,4-butanediol, 1,3-propanediol and mixtures thereof and wherein thelevel of said copolyetherester elastomer is from about 5 to about 50weight percent based on the total weight of the copolyetheresterelastomers.

As a result of their excellent tear strengths, tensile strengths, flexlives, abrasion resistances, and broad useful end-use temperatureranges, thermoplastic copolyetherester elastomers are used in a widerange of applications including for example wire and cable coatings,automotive applications, components for household appliances, componentsfor buildings or mechanical devices and tubes and pipes for conveyingfluids. Examples of suitable copolyetherester elastomers arecommercially available under the trademark Hytrel® copolyetheresterelastomer from E. I. du Pont de Nemours and Company, Wilmington, Del.

The flame retardant polymer compositions of the invention also comprisemelamine cyanurate.

Melamine cyanurate, also known as melamine-cyanuric acid adduct ormelamine-cyanuric acid complex, is a crystalline complex formed from a1:1 mixture of melamine and cyanuric acid. Melamine cyanurate is thecommonly used name for adducts of 2,4,6-triamino-1,3,5-triazine(melamine) and 2,4,6-trihydroxy-1,3,5-triazine or its tautomer((iso)cyanuric acid) as described for example in U.S. Pat. No.4,180,496.

Preferably, the amount of melamine cyanurate present in the flameretardant polymer composition of the present invention is higher than orequal to 10 weight percent based on the total weight of the flameretardant polymer composition. Lower amounts of melamine cyanurate maynot be effective enough to impart flame retardance to the polymercomposition. More preferably, the amount of melamine cyanurate presentin the flame retardant polymer composition of the present invention isfrom 10 to 30 weight percent, even more preferably from 15 to 25 weightpercent, the weight percent being based on the total weight of the flameretardant polymer composition. Amounts higher than 30 weight percent maydetrimental to the mechanical properties of the flame retardant polymercomposition.

In contrast to many flame retardant polymer compositions described inthe art, the flame retardant polymer compositions of the presentinvention are free of organic or inorganic phosphinate flame retardantderivatives such as those described in U.S. Pat. No. 6,255,371 (e.g.aluminium diethylphosphinate) and in U.S. Pat. No. 7,700,680 (e.g.aluminiun phosphinate).

The flame retardant polymer compositions of the present inventioncomprise one or more epoxy-containing compounds. Examples of suitableepoxy-containing compounds include without limitation epoxy-containingpolyolefins, other epoxy-containing polymers, glycidyl ethers ofpolyphenols, bisphenol epoxy resins and epoxy novolac resins.

Epoxy-containing polyolefins are polyolefins, preferably polyethylene,that are functionalized with epoxy-containing groups. As used herein,the term “functionalized with epoxy-containing groups” refers to thefact that the epoxy-containing groups are grafted onto the polyolefinand/or copolymerized with the olefin comonomer.

One class of epoxy-containing polyolefin useful in the practice of theinvention comprises copolymers of an olefin comonomer and a comonomerthat contains an epoxy-containing group. Examples of suitable comonomersinclude unsaturated epoxides comprising from four to eleven carbonatoms, such as glycidyl (meth)acrylate, allyl glycidyl ether, vinylglycidyl ether and glycidyl itaconate. Glycidyl (meth)acrylates (GMA)are particularly preferred copolymerizable monomers. By (meth)acrylateis meant herein that the compound may be either an acrylate, amethacrylate, or a mixture of the two. Ethylene/glycidyl (meth)acrylatecopolymers may further contain copolymerized units of vinyl acetate oran alkyl (meth)acrylate having from one to six carbon atoms and anα-olefin having 1-8 carbon atoms. Representative alkyl (meth)acrylatesinclude methyl (meth)acrylate, ethyl (meth)acrylate, propyl(meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, hexyl(meth)acrylate, or combinations of these. Of note are ethyl acrylate andbutyl acrylate.

It is preferred that the epoxy-containing polyolefins, when used,contain about 0.5 to about 20 weight percent of repeat units derivedfrom monomers containing epoxy functional groups, preferably about 1.0to about 10 weight percent, based on the weight of the epoxy-containingpolyolefin. There may be more than one type of repeat unit derived fromfunctionalized monomer present in the epoxy-containing polyolefin.

Polymers other than the above-described epoxy-containing olefincopolymers are also useful in the practice of the invention. Forexample, graft polymers which contain epoxy functional groups arewell-known materials. They may comprise unsaturated epoxides comprisingfrom four to eleven carbon atoms, such as glycidyl (meth)acrylate, allylglycidyl ether, vinyl glycidyl ether and glycidyl itaconate, glycidyl(meth)acrylates (GMA) being particularly preferred. Such unsaturatedepoxides are usually “attached” to the polymer by reacting theepoxy-containing compounds with an existing polymer, (i.e. graftingsmall molecules onto an already existing polymer). Such unsaturatedexpoxides may also be incorporated into a polymer by copolymerizingmonomers containing the desired functional group when the polymermolecules are prepared by copolymerization. As an example of grafting,glycidyl methacrylate may be grafted onto a hydrocarbon rubber. Theresulting grafted polymer has epoxy functional groups attached to it.The epoxy-containing polymers may also be thermoplastic acrylic polymersthat contain copolymerized epoxy group-containing comonomers or graftedepoxy-containing molecules. Such thermoplastic acrylic polymers areoften prepared by polymerizing acrylic acid, acrylate esters (such asmethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butylacrylate, n hexyl acrylate, and n-octyl acrylate), methacrylic acid, andmethacrylate esters (such as methyl methacrylate, n-propy) methacrylate,isopropyl methacrylate, n-butyl methacrylate (BA), isobutylmethacrylate, p-octyl methacrylate, glycidyl methacrylate (GMA) and thelike). Copolymers derived from two or more of the forgoing types ofmonomers may also be used, as well as copolymers made by polymerizingone or more of the forgoing types of monomers with styrene,acrylonitrile, butadiene, isoprene, and the like. Part or all of thecomponents in these copolymers preferably have a glass transitiontemperature of not higher than 0° C. Preferred monomers for thepreparation of a thermoplastic acrylic polymer are methyl acrylate,n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, n-hexylacrylate, and n-octyl acrylate.

It is preferred that the epoxy group-containing thermoplastic acrylicpolymer is prepared from a thermoplastic acrylic polymer that has acore-shell structure. The core-shell structure is one in which the coreportion preferably has a glass transition temperature of 0° C. or less,while the shell portion preferably has a glass transition temperaturehigher than that of the core portion. The core portion may be graftedwith silicone. The shell section may be grafted with a low surfaceenergy substance such as silicone, fluorine, and the like. An acrylicpolymer with a core-shell structure that has low surface energysubstances grafted to the surface will aggregate with itself during orafter mixing with the copolyetherester thermoplastic elastomer and othercomponents of the composition described herein and can be easilyuniformly dispersed in the composition.

When present, the preferred amount of epoxy-containing polyolefinsand/or other epoxy-containing polymers in the flame retardant polymercomposition is from at or about 0.5 to at or about 30 weight percent, ormore preferably from at or about 1 to at or about 15 weight percent, theweight percentages being based on the total weight of the flameretardant polymer composition.

Other examples of suitable epoxy-containing compounds include bisphenolepoxy resins. Such resins are condensation products having epoxyfunctional groups and a bisphenol moiety. Examples include withoutlimitation products obtained from the condensation of bisphenol A andepichlorohydrin and products obtained from the condensation of bisphenolF and epichlorohydrin.

Another class of suitable epoxy-containing compounds is epoxy novolacresins. These resins are condensation products of an aldehyde, such asfor example formaldehyde and an aromatic hydroxyl-containing compoundsuch as for example phenol or cresol.

A preferred epoxy-containing compound suitable for use in thecomposition of the invention is a diphenolic epoxy condensation polymer.As used herein, “diphenolic epoxy condensation polymer” means acondensation polymer having epoxy functional groups, preferably as endgroups, and a diphenol moiety within the polymer. Such diphenolic epoxycondensation polymers are well-known to those of ordinary skill in theart.

Preferred diphenolic epoxy condensation polymers include condensationpolymers of epichlorohydrin with a diphenolic compound. Also preferredis a 2,2-bis(p-glycidylhydroxyphenyl) propane condensation product with2,2-bis(p-hydroxyphenyl)propane and similar isomers. Particularlypreferred is a 2,2-bis(4-hydroxyphenyl)propane-epichlorohydrin copolymerthat has an epoxy functional group equivalent weight of 600-700g/equivalent, supplied by Momentive Chemical Solutions under thetradename Epikote™ EP1002F.

Preferred epoxy-containing compounds comprise at least two epoxy groupsper molecule of the compound, more preferably at least three epoxygroups per molecule of the compound, and more preferably at least fourepoxy groups per molecule of the compound. Even more preferably,multifunctional epoxy-containing compounds comprise between two and fourepoxy groups per molecule of the epoxy-containing compound. The epoxygroups preferably comprise glycidyl ethers, and even more preferably,glycidyl ethers of phenolic compounds. These epoxy-containing compoundsmay be polymeric or non-polymeric, with non-polymeric being preferred.An example of an epoxy-containing compound is a tetraglycidyl ether oftetra (parahydroxyphenyl) ethane. A particularly preferred example of acommercially available epoxy-containing compound is tetraglycidyl etherof tetraphenol ethane with a functionality of 3.5 and an epoxyfunctional group equivalent weight of 195-230 g/equivalent suppliedunder the Tradename EPON® 1031 from Momentive Specialty Chemicals, Inc.The preferred amount of the preferred epoxy-containing compounds of theinvention is typically at or about 0.5 to 4 weight percent of suchpreferred epoxy-containing compound based on the total weight of theflame retardant polymer composition.

The preferred amount of epoxy-containing compound present in the flameretardant polymer composition of the present invention is such that itprovides from at or about 2.5 to about 10 milliequivalents of totalepoxy functionality based on a hundred grams of the total weight of theflame retardant polymer composition.

For each individual epoxy-containing compound present in thecompositions of the invention the epoxy functional group equivalentweight is the weight of the epoxy-containing compound divided by thenumber of epoxy functional groups in the molecule. For each compositionthe total epoxy functional group equivalent weight is therefore definedby the number of “moles” or molar equivalent of epoxy functional groupsper kilogram of the composition.

Apart from melamine cyanurate, the flame retardant polymer compositionsof the present invention may further comprise aromatic phosphate esterflame retardants such as those described in EP 0 947 547, the disclosureof which is incorporated by reference.

Preferred aromatic phosphate ester flame retardants are selected fromthe group consisting of resorcinol bis(di-2,6-dimethylphenyl phosphate),described in Japanese Kokai H9-143350 and available under the tradenamePX-200 from Daihachi Chemical Industry Corporation, and bisphenolbis(di-2,6-dimethylphenyl phosphate) available under the tradenamePX-202 from Daihachi Chemical Industry Corporation.

When used, the preferred amount of aromatic aromatic phosphate esterflame retardant present in the flame retardant polymer composition ofthe present invention is lower than or equal to 15 weight percent basedon the total weight of the flame retardant polymer composition. Morepreferably, the amount of aromatic aromatic phosphate ester flameretardant present in the flame retardant polymer composition of thepresent invention is from 2 to 12 weight percent based on the totalweight of the flame retardant polymer composition.

The flame retardant polymer composition of the present invention mayalso optionally comprise a phosphite. The phosphite compounds that canbe used in the flame retardant polymer composition according to thepresent invention may be monophosphites, diphosphites andpolyphosphites.

Suitable monophosphites are, for example, trialkylphosphites,dialkylaryl phosphites, alkyldiaryl phosphites and triaryl phosphites.The aryl groups in these phosphites may be linear as well as branched,may comprise cyclic and/or aromatic groups and may also comprisehetero-atom containing substituents. The aryl groups in these phosphitesmay be unsubstituted aryl groups as well as substituted aryl groups,wherein the substituted aryl groups may comprise, for example, alkylgroups and/or hetero-atom containing substituents.

An example of a suitable trialkylphosphite is tri-nonyl phosphite. Anexample of a suitable dialkylaryl phosphite is diiso-octyl octylphenylphosphite. An example of a suitable alkyldiaryl phosphite is diphenyliso-octylphosphite and an example of a suitable triaryl phosphite istriphenyl phosphite.

Suitable diphosphites are, for example, biphenylene diphosphites,pentaerythritol diphosphites, 4,4′-iso-propylidenediphenol diphosphites,and dipropyleneglycol diphosphites. The phosphite groups in thesediphosphites suitably comprise alkyl and/or aryl groups, wherein thealkyl and aryl groups suitably are chosen from the alkyl and aryl groupsmentioned above for the monophosphites.

An example of a suitable biphenylene diphosphite istetrakis-(2,4-di-tertbutyl-phenyl)-4,4′-biphenylene diphosphites.Examples of suitable pentaerythritol diphosphites arebis(2,4-di-t-butylphenyl)pentaerythritol diphosphite andbis-(2,4-dicumylphenyl)pentaerythritol diphosphite. An example of asuitable 4,4′-iso-propylidenediphenol diphosphite is tetrakis(iso-decyl)iso-propylidenediphenol diphosphite, and an example of a suitabledipropyleneglycol diphosphite is tetraphenyl dipropyleneglycoldiphosphite.

Preferably, the phosphite stabilizer is a diphosphite compound, morepreferably a pentaerythritol diphosphite.

When used, the preferred amount of phosphite present in the flameretardant polymer compositions of the present invention is lower than orequal to 2 weight percent based on the total weight of the flameretardant polymer composition. More preferably, the amount of phosphitepresent in the flame retardant polymer composition of the presentinvention is from 0.1 to 1 weight percent based on the total weight ofthe flame retardant polymer composition.

When an aromatic phosphate ester is present in the flame retardantcomposition, either in the presence or absence of a phosphite compound,the amount of epoxy-containing compound is most effective when adjustedas follows: i) when the flame retardant polymer composition comprises anaromatic phosphate ester flame retardant and a phosphite, the amount ofepoxy-containing compound present is such that the total epoxyfunctional group equivalent weight is at least about 32 milliequivalentsper kg of the combined weight of the one or more copolyetheresterthermoplastic elastomers and the aromatic phosphate ester flameretardant and ii) when the flame retardant polymer composition comprisesan aromatic phosphate ester flame retardant in the absence of phosphite,the amount of epoxy-containing compound present is such that the totalepoxy functional group equivalent weight is at least about 56milliequivalents per kg of the combined weight of the one or morecopolyetherester thermoplastic elastomers and the aromatic phosphateester flame retardant.

The flame retardant polymer compositions described herein may furthercomprise additives that include, but are not limited to, one or more ofthe following components as well as combinations of these: metaldeactivators, such as hydrazine and hydrazide; heat stabilizers;antioxidants; modifiers; colorants, lubricants, fillers and reinforcingagents, impact modifiers, flow enhancing additives, antistatic agents,crystallization promoting agents, conductive additives, viscositymodifiers, nucleating agents, plasticizers, mold release agents, scratchand mar modifiers, drip suppressants, adhesion modifiers and otherprocessing aids known in the polymer compounding art. Preferably, theadditives are selected from the group consisting of stabilizers,processing agents, metal deactivators, antioxidants, UV stabilizers,heat stabilizers, dyes and/or pigments. When used, additional additivesare preferably present in amounts of about 0.05 to about 10 weightpercent, based on the total weight of the flame retardant polymercomposition.

The flame retardant polymer compositions described herein are melt-mixedblends, wherein all of the polymeric components are well-dispersedwithin each other and all of the non-polymeric ingredients arewell-dispersed in and bound by the polymer matrix, such that the blendforms a unified whole. Any melt-mixing method may be used to combine thepolymeric components and non-polymeric ingredients of the presentinvention.

The polymeric components and non-polymeric ingredients of the flameretardant polymer compositions of the invention may be added to a meltmixer, such as, for example, a single or twin-screw extruder; a blender;a single or twin-screw kneader; or a Banbury mixer, eithersimultaneously through a single step addition, or in a stepwise fashion,and then melt-mixed. When adding the polymeric components andnon-polymeric ingredients in a stepwise fashion, a portion of thepolymeric components and/or non-polymeric ingredients are first addedand melt-mixed with the remaining polymeric components and non-polymericingredients being subsequently added and further melt-mixed until awell-mixed composition is obtained.

The flame retardant polymer compositions described herein may be shapedinto articles using methods known to those skilled in the art, such asinjection molding, blow molding, injection blow molding, extrusion,thermoforming, melt casting, vacuum molding, rotational molding,calendar molding, slush molding, filament extrusion and fiber spinning.Such articles may include films, fibers and filaments, wire and cablecoatings; photovoltaic cable coatings, optical fiber coatings, tubingand pipes; fabrics or texiles made fibers and filaments, e.g., used inclothing or carpets; films and membranes such breathable membranes inroofing and building/construction; motorized vehicle parts such as bodypanels, air bag doors, dashboards, engine covers, rocker panels or airfilter covers; components for household appliances, such as washers,dryers, refrigerators and heating-ventilation-air conditioningappliances; connectors in electrical/electronic applications; componentsfor electronic devices, such as computers; components for office-,indoor-, and outdoor-furniture; and footwear components.

Preferably, the flame retardant polymer compositions of the presentinvention are used to make insulated wire and cable coatings such asinsulated layers or jackets for cables and wires.

Examples

The invention is further illustrated by certain embodiments in theexamples below which provide greater detail for the compositions, usesand processes described herein.

Materials

The following materials were used to prepare the flame retardant polymercompositions described herein and the compositions of the comparativeexamples.

Copolyetherester Thermoplastic Elastomer 1 (TPC-1): a copolyetheresterelastomer comprising about 7.8 weight percent of poly(tetramethyleneoxide) having an average molecular weight of about 1000 g/mol aspolyether block segments, the weight percentage being based on the totalweight of the copolyetherester elastomer, the short chain ester units ofthe copolyetherester being polybutylene terephthalate segments. Asrequired for the manufacturing process and well-known to those skilledin the art, the copolyetherester elastomer contained up to 6 weightpercent of heat stabilizers, antioxidants and metal deactivators.

Copolyetherester Thermoplastic Elastomer 2 (TPC-2): a copolyetheresterelastomer comprising about 26.4 weight percent of poly(tetramethyleneoxide) copolymerized units having an average molecular weight of about1000 g/mol as polyether block segments, the weight percentage beingbased on the total weight of the copolyetherester elastomer, the shortchain ester units of the copolyetherester being polybutyleneterephthalate segments. As required for the manufacturing process andwell-known to those skilled in the art, the copolyetherester elastomercontained up to 6 weight percent of heat stabilizers, antioxidants andmetal deactivators.

Copolyetherester Thermoplastic Elastomer 3 (TPC-3): a copolyetheresterelastomer comprising about 15.9 weight percent of poly(tetramethyleneoxide) having an average molecular weight of about 1000 g/mol aspolyether block segments, the weight percentage being based on the totalweight of the copolyetherester elastomer, the short chain ester units ofthe copolyetherester being polybutylene terephthalate and polybutyleneisophthalate segments. As required for the manufacturing process andwell-known to those skilled in the art, the copolyetherester elastomercontained up to 6 weight percent of heat stabilizers, antioxidants andmetal deactivators.

Melamine cyanurate flame retardant (MC-1): Melapur®, melamine cyanurate,having a D98 max of 25 μm, supplied by BASF.

Melamine cyanurate flame retardant (MC-2): FT-6120 MC15, melaminecyanurate, having a D98 max of 15 μm, supplied by ICL IndustrialProducts.

Phosphinate flame retardant: Exolit® OP935, an aluminum salt ofdiethylene phosphinate having a D90 max of 7.506 microns, supplied byClariant Corporation.

Epoxy-1: Epikote™ EP1002F, a2,2-bis(4-hydroxyphenyl)propane-epichlorohydrin copolymer, supplied byMomentive Chemical Solutions; epoxy functional group equivalent weightof 600-700 g/eq.

Epoxy-2: Epon™ 1031, tetraglycidyl ether of tetraphenol ethane with afunctionality of 3.5, supplied by Momentive Chemical Solutions; epoxyfunctional group equivalent weight of 195-230 g/eq.

Phosphite: Doverphos® S9228T, a Bis (2,4-dicumylphenyl) pentaerythritoldiphosphite containing up to 2% triisopropanolamine, supplied by DoverChemical Corporation.

Phosphate-1: PX-200, a resorcinol bis(di-2,6-dimethylphenyl phosphate),supplied by Daihachi Chemical Industry Corporation.

Phosphate-2: PX-202, a bisphenol bis(di-2,6-dimethylphenyl phosphate),supplied by Daihachi Chemical Industry Corporation.

In Tables 1-2, compositions of the Examples are identified as “E” andcompositions of the Comparative Examples are identified as “C”.

Preparative Methods

Flame retardant polymer compositions of the invention and comparativecompositions were prepared as follows: the above described materials, inthe amounts listed in Tables 1 and 2, were melt blended in a twin screwextruder. The compounded melt blended mixtures of comparative examplesC4, C5 and of all examples were extruded in the form of laces orstrands, cooled in a water bath, chopped into granules and placed insealed aluminum lined bags in order to prevent moisture pick-up.

Comparative example C1-C3 compositions, containing copolyetherestercopolymers TPC-1 and TPC-2 in a weight ratio of 4:1, without any flameretardant, and without any epoxy-containing compound (Sample C1) orcontaining epoxy-containing compound (Samples C2 and C3) in the amountslisted in Table 1, were melt extruded in narrow flat strips on astandard extruder operated at a barrel temperature of 225° C.

The comparative example C5 composition, containing the samecopoleytherester copolymer blend as comparative examples C1-C3, and inaddition containing melamine cyanurate MC-1 and phosphate-1 in theamounts shown in Table 2, was melt blended in a 16 mm twin screwextruder (Prism 16) operated at a barrel temperature of about 240° C., ascrew speed of about 300 rpm and a throughput of about 1 kg/hr.

Comparative examples C6-C8 compositions, containing the samecopolyetherester copolymer blend, slightly lower amounts of melaminecyanurate MC-1 and phosphate-1 as the comparative example C5, and inaddition containing epoxy-containing compound and phosphite materials inthe amounts listed in Table 2, were melt extruded in narrow flat stripson a standard extruder operated at a barrel temperature of 225° C.

Example E1-E9 compositions, containing the same copolyetherestercopolymer blend as comparative examples C5-C8, melamine cyanurate flameretardant MC-2 and epoxy-1 in the amounts listed in Tables 1 and 2, weremelt blended in a 30 mm twin screw extruder (ZSK 30 mm) operated at abarrel temperature of 230° C., a screw speed of about 250 rpm and athroughput of 13-17 kg/hr. In addition, example E1-E9 compositionscontained epoxy-2 and/or phosphite in the amounts listed in Tables 1 and2. The Example E3 composition contained copolyetherester elastomer TPC-3instead of TPC-2. Examples E1-E3 further contained a phosphate flameretardant.

Example E10-E22 and comparative example C4 compositions, containingsimilar compositions as examples E1-E9 but with varying levels ofmaterials in the amounts listed in Tables 1 and 2, were melt blended ina 30 mm twin screw extruder (ZSK 30 mm) operated at a barrel temperatureof 230° C., a screw speed of about 200 rpm and a throughput of 11-16kg/hr. Comparative example C4 did not contain melamine cyanurate flameretardant but instead contained phosphinate flame retardant.

Test Methods

Flammability testing was performed according to UL 94 test standard, 20mm vertical burning test. Test specimens were formed from thecompositions of the invention (Samples E1-E22) and from a comparativecomposition (Sample C4) by injection molding the compositions in theform of test bars having dimensions of 125 mm long by 13 mm wide and athickness of 0.8 mm. Prior to injection molding, the granules of theflame retardant compositions prepared according to the above-describedmethods were dried to provide granulated compositions having a moisturelevel below 0.08 percent. For comparative compositions C6-C8, testspecimens were formed by cutting test specimens from an extruded flatstrip in the form of test bars having dimensions of 125 mm long by 13 mmwide and a thickness of 1.8 mm. Before measurement, the test specimenswere conditioned for 48 hours at 23° C. and 50% relative humidity. Testspecimens were clamped with the longitudinal axis of the specimen in thevertical direction, so that the lower end of the specimen was 300 mmabove a horizontal layer of dry absorbent surgical cotton. A burnerproducing a blue flame 20 mm high was placed so that the flame wasapplied centrally to the mid-point of the bottom edge of the specimenfor 10 seconds. After the application of the flame to the specimen for10 seconds, the burner was withdrawn from the sample and the after-flametime, t1, was measured. When after-flaming of the test specimen ceased,the burner was again placed beneath the specimen for an additional 10seconds. The flame was then withdrawn from the test specimen and thesecond after-flame time, t2, was measured. Materials are classifiedaccording to the test specifications as V-0, V-1 or V-2, based on thebehavior of the material during burning, V-2 being the least demandingclassification. When the composition failed to meet the criteria for theleast demanding classification (V-2), it is reported as “failed” in thetables.

Mechanical property measurement was conducted as follows. Prior toinjection molding, the granules of the flame retardant compositions ofthe invention (Samples E1-E22) and from a comparative composition(Sample C4) prepared according to the above-described method were driedto provide granulated compositions having a moisture level below 0.08percent. Tensile stress at break and elongation at break were measuredaccording to the method ISO 527 using injection molded ISO tensile bar5A samples of thickness of 2 mm for the compositions of the invention(Samples E1-E22) and comparative composition (Sample C4), or cutting 5Atensile bar specimen from an extruded flat strip for comparativecompositions C1-C3 and C6-C8. The length of the tensile bars was 75 mmand the test speed was 50 mm/min.

Electrical performance measurement was conducted as follows.

Test specimens were formed from the compositions of the invention(Samples E1-E22) and from comparative composition (Sample C4) byinjection molding the compositions in the form of plaques havingdimensions of 100 mm by 100 mm wide and a thickness of 1.0 mm. Forcomparative compositions C1-C3, C5 and C6-C8, test specimens were formedby compression molding the compositions in the form of plaques havingthe same dimensions as for the compositions of the invention. The volumeresistivity of the molded plaques was measured after submitting theplaques to different conditioning treatments:

-   -   (i) Volume resistivity in air at 23° C.: The plaques were        allowed to rest at least 16 hrs at room temperature after        molding. Volume resistivity from such plaques was measured in        air at room temperature according to IEC 60093 by applying a DC        potential of 500 V for 60 seconds prior to each reading. The        duration of each reading was 60 seconds.    -   (ii) Volume resistivity after submersion in water: Each polymer        plaque to be measured was brought into contact with a copper        plate of the same dimensions as the polymer plaque and they were        pressed together by means of mechanical screws. The        polymer-copper plaques were immersed in a closed water bath        placed in a heated oven at 75° C. for 1 day, 7 days or 14 days        respectively. The volume resistivity from the polymer plaques        was measured immediately upon removal from the water bath.

Compositions of the invention have good flammability performance of atleast V-2 at a thickness of 0.8 mm, elongation at break of at least 30%,and good electrical insulation performance as follows: (i) volumeresistivity in air at 23° C. greater than or equal to 6000 GOhm·m and(ii) volume resistivity in water at 75° C. at any one between 1 and 14days of greater than or equal to 500 GOhm·m. In the tables, compositionshaving volume resistivity of greater than 500 GOhm·m in water at 75° C.during 1, 7 or 14 days are reported as “Pass”, the ones having volumeresistivity of less than 500 GOhm·m in water at 75° C. during 1, 7 or 14days are reported as “Fail”.

The total epoxy functional group equivalent weight for each of thecompositions is shown in the tables. For each individualepoxy-containing compound used the epoxy functional group equivalentweight (EEW) is the weight of the epoxy-containing compound over thenumber of epoxy groups in the molecule. Calculations were based on theaverage epoxy functional group equivalent weight: for Epoxy-1, 650 g/eq,and for Epoxy-2, 210 g/eq. For each composition the total epoxyfunctional group equivalent weight is provided per weight of the mixtureof TPCs and phosphates, as(A+B)/(w_(TPC-1)+w_(TPC-2)+w_(TPC-3)+w_(Phosphate-1)+w_(Phoshate-2)),where A=w_(epoxy-1)/EEW_(epoxy-1), B=w_(epoxy-2)/EEW_(epoxy-2) and w_(i)is the weight percent of the material i with respect to the total weightof the flame retardant polymer composition. In addition the total epoxyfunctional group equivalent weight per weight of the mixture of melaminecyanurate and phosphate flame retardants is provided as(A+B)/(w_(MC-1)+w_(MC-2)+w_(Phosphate-1)+w_(Phoshate-2)).

The data presented in Table 1 indicate that the comparative compositioncomprising only copolyetherester elastomers (Sample C1) exhibited goodmechanical performance and good volume resistivity as reflected by avalue of volume resistivity of greater than 6000 GOhm·m in air at 23° C.and greater than 500 GOhm·m in water at 75° C. during 14 days. Theincorporation of epoxy-containing compounds in the composition of SampleC1 (Samples C2 and C3) retained a good performance. However compositionsC1-C3 fail in flammability performance. The incorporation of melaminecyanurate flame retardant in the similar composition to comparativeexample C3 (Sample E4) surprisingly resulted in an improvement of thevolume resistivity in air at 23° C. while it exhibited good volumeresistivity during hydrolysis at 75° C. and a good flammabilityperformance. This sample had a total epoxy functional group equivalentweight of 57.2 milliequivalent/kg TPC and 218 milliequivalent/kg MC.Further increase of the epoxy functional group equivalent weight (sampleE5) maintained a good performance. Incorporation of a copolyetheresterelastomer containing polybutylene isophthalate hard segments TPC-3instead of the copolyetherester elastomer containing only polybutyleneterephthalate hard segments to the composition of E5 (sample E13) oreven at a lower TPC-1:TPC-3 weight ratio (sample E14) surprisinglyresulted in a significant improvement of the volume resistivity in airat 23° C. while it presented good volume resistivity during hydrolysisat 75° C. and a good flammability performance. Examples E4-E5 andE13-E14 incorporating no phosphate and no phosphite had a total epoxyfunctional group equivalent weight of greater than 57.2milliequivalent/kg of TPC and greater than 218 milliequivalent/kg MCIncorporation of a phosphite at a level of 0.3 weight percent to 1weight percent in combination with epoxy-containing compoundssurprisingly provided a further improvement of volume resistivity underall conditions while retaining good mechanical and flammabilityperformance (Samples E6-E9 and E15-E17, E21). And presented a goodperformance even at a low total epoxy functional group equivalent weightof 32.8 milliequivalent/kg TPC and 123 milliequivalent/kg MC.

Incorporation of an organic phosphinate instead of melamine cyanurate incombination with epoxy-1 and epoxy-2 (comparative sample C4) resulted ingood volume resistivity and flammability performance but the sampledemonstrated poor extrudability performance even at a relatively lowlevel of the epoxies, as indicated by a difficulty in extruding thecomposition and by a very low elongation at break of about 4%.

The data presented in Table 2 indicate that the comparative compositioncomprising only the flame retardant mixture of melamine cyanurate andphosphate-1 (Sample C5) exhibited an unacceptable volume resistivityupon only 1 day submersion in water at 75° C., as reflected by a valueof volume resistivity of less than 500 GOhm·m. The incorporation of theepoxy-1 in the flame retardant composition incorporating melaminecyanurate and phosphate-1 at a level of 1.6 weight percent alone or withphosphite at a level of 0.3 weight percent or with epoxy-2 at a level of0.4 weight percent (samples C6-C8) did not significantly improve thevolume resistivity during hydrolysis at 75° C. failing the electricalinsulation test. Comparative Examples C5-C8 had a total epoxy functionalgroup equivalent weight of less than 55.8 milliequivalent/kg of thecopolyetherester elastomer and phosphate mixture and less than 145.3milliequivalent/kg of the melamine cyanurate and phosphate mixture. Theincorporation of a higher level of total epoxy functional groupequivalent weight in the mixture containing the melamine cyanurate andphosphate flame retardants provided a good volume resistivity under allconditions (all Examples E1-E3, E10-E12). Furthermore such compositionsprovided an advantageously good flammability performance (Samples E1-E3)and an advantageously good elongation at break (Samples all ExamplesE1-E3, E10-E12) compared to comparative examples C5-C8 and even comparedto all examples in Table 1 incorporating melamine cyanurate only flameretardant. Incorporation of a copolyetherester elastomer containingpolybutylene isophthalate hard segments TPC-3 instead of thecopolyetherester elastomer containing only polybutylene terephthalatehard segments surprisingly resulted in a significant improvement of thevolume resistivity in air at 23° C. while it presented good volumeresistivity during hydrolysis at 75° C. and a good flammabilityperformance (Samples E3, E10-E12). Examples E1-E3 and E10-E12incorporating no phosphite had a total epoxy functional group equivalentweight of greater than 55.8 milliequivalent/kg of (TPC+phosphate) andgreater than 145.3 milliequivalent/kg of (MC+phosphate). Incorporationof a phosphite at a level of 0.3 weight percent to 0.4 weight percent incombination with epoxy-containing compounds surprisingly provided afurther improvement of volume resistivity under all conditions even at alower total epoxy functional group equivalent weight compared to samplesincorporating no phosphite while retaining good mechanical andflammability performance (Samples E18-E22).

TABLE 1 C1 C2 C3 E4 E5 E6 E7 E8 E9 TPC-1 75.4 74.2 74.1 61 59.7 59.5 6059 61 TPC-2 18.8 18.5 18.3 15.2 15 14.9 15.1 14.7 15.2 TPC-3 HeatStabilizers/ 5.8 5.7 5.6 1.8 1.8 2.3 2.3 2.3 1.5 Metal DeactivatorsEpoxy-1 1.6 1.6 1.6 3 3 1.6 3 1.6 Epoxy-2 0.4 0.4 0.5 0.4 Phosphite 0.31 1 0.3 MC-2 20 20 20 20 20 20 Phosphinate Total (weight percent) 100100 100 100 100 100 100 100 100 TPC-1:TPC-2 (TPC-3) (wt/wt) 4 4 4 4 4 44 4 4 Epoxy functional group 0 2.46 4.36 4.36 7.00 4.62 2.46 4.62 4.36equivalent weight (meq per 100 g total) Epoxy functional group 0 26.547.2 57.2 93.7 62.1 32.8 62.7 57.2 equivalent weight (meq per kg (TPC +phosphate)) Epoxy functional group 0 — — 218 350 231 123 231 218equivalent weight (meq per kg (MC + phosphate)) Tensile stress at break(MPa) 41 33.4 39 24 22 23 20 22 23 Elongation at break (%) 466 347 42933 39 36 41 34 38 UL-V rating Fail Fail Fail V2 V2 V0 V2 V2 V2 Volumeresistivity (1E2 GOhm · m)^([1]) in air at 23° C. 126 191 205 303 290530 432 356 241 In water at 75° C.  1 day Pass Pass Pass Pass Pass PassPass Pass Pass 7 days Pass Pass Pass Pass Pass Pass Pass Pass Pass 14days  Pass Pass Pass Pass Pass Pass Pass Pass Pass E13 E14 E15 E16 E17E21 C4 TPC-1 59.7 49.7 59.5 59.5 49.4 59.8 61   TPC-2 14.9 TPC-3 15 2514.9 25 15 15.2  Heat Stabilizers/ 1.8 1.8 2.3 2.3 2.3 2.3 1.8 MetalDeactivators Epoxy-1 3 3 3 3 3 2.3 1.6 Epoxy-2 0.5 0.5 0.2 0.4 Phosphite0.3 0.3 0.3 0.4 MC-2 20 20 20 20 20 20 Phosphinate 20   Total (weightpercent) 100 100 100 100 100 100 100    TPC-1:TPC-2 (TPC-3) (wt/wt) 4 24 4 2 4 4   Epoxy functional group 7.00 7.00 4.62 4.62 4.62 4.49  4.36equivalent weight (meq per 100 g total) Epoxy functional group 93.7 93.762.1 62.1 62.1 60.0 57.2  equivalent weight (meq per kg (TPC +phosphate)) Epoxy functional group 350 350 231 231 231 225 218   equivalent weight (meq per kg (MC + phosphate)) Tensile stress at break(MPa) 21.8 20.1 21.6 19.5 19.3 20.5 33.1  Elongation at break (%) 41 5540 46 74 43 4*  UL-V rating V2 V2 V2 V2 V2 V2 V2 Volume resistivity (1E2GOhm · m)^([1]) in air at 23° C. 1096 755 348 222 691 1307 1341    Inwater at 75° C.  1 day Pass Pass Pass Pass Pass Pass Pass 7 days PassPass Pass Pass Pass Pass Pass 14 days  Pass Pass Pass Pass Pass PassPass ^([1])The designation 1E2 GOhm · m indicates that reported valuesare 10⁻² times the measured value. For example, the reported value 126is equivalent to a measured value of 12600.

TABLE 2 C5 C6 C7 C8 E1 E2 E3 E10 TPC-1 52.8 53.3 52.7 52.9 51.8 51.851.8 51.8 TPC-2 13.2 13.3 13.1 13.3 12.9 12.9 TPC-3 12.9 12.9 Heatstabilizers/ 4.0 1.8 2.3 1.8 1.8 1.8 1.8 1.8 Metal deactivators Epoxy-11.6 1.6 1.6 3 3 3 3 Epoxy-2 0.4 0.5 0.5 0.5 0.5 Phosphite 0.3 MC-1 20 1818 18 MC-2 18 18 18 18 Phosphate-1 10 12 12 12 12 Phosphate-2 12 12 12Total (weight percent) 100 100 100 100 100 100 100 100 TPC-1:TPC-2(wt/wt) 4 4 4 4 4 4 4 4 Epoxy functional group 0 2.46 2.46 4.36 7.007.00 7.00 7.00 equivalent weight (meq per 100 g total) Epoxy functionalgroup 0 31.3 31.6 55.8 91.3 91.3 91.3 91.3 equivalent weight (meq per kg(TPC + phosphate)) Epoxy functional group 0 82 82 145.3 233 233 233 233equivalent weight (meq per kg (MC + phosphate)) Tensile stress at break(MPa) 18.9 21.5 21.0 20 19 17 19.2 Elongation at break (%) 55.9 12.131.5 81 71 96 75 UL-V rating V2 V2 V2 V0 V0 V0 V2 Volume Resistivity(1E2 GOhm · m)^([1]) in air at 23° C. 78 37 56 39 57.8 60.9 570 1440 inwater at 75° C.  1 day Fail Fail Pass Pass Pass Pass Pass Pass 7 daysFail Fail Pass Pass Pass Pass Pass 14 days  Fail Fail Fail Pass PassPass Pass E11 E12 E18 E19 E20 E22 TPC-1 51.8 43 51.5 51.5 43 51.9 TPC-2TPC-3 12.9 21.7 12.9 12.9 21.4 12.9 Heat stabilizers/ 1.8 1.8 2.3 2.32.3 2.3 Metal deactivators Epoxy-1 3 3 3 3 3 2.3 Epoxy-2 0.5 0.5 0.2Phosphite 0.3 0.3 0.3 0.4 MC-1 MC-2 18 18 18 18 18 18 Phosphate-1 12 1212 12 12 Phosphate-2 12 Total (weight percent) 100 100 100 100 100 100TPC-1:TPC-2 (wt/wt) 4 2 4 4 2 4 Epoxy functional group 7.00 7.00 4.624.62 4.62 4.49 equivalent weight (meq per 100 g total) Epoxy functionalgroup 91.3 91.3 60.5 60.5 60.5 58.4 equivalent weight (meq per kg (TPC +phosphate)) Epoxy functional group 233 233 154 154 154 150 equivalentweight (meq per kg (MC + phosphate)) Tensile stress at break (MPa) 19.818.7 18.2 18.5 15.6 18 Elongation at break (%) 125 272 85 104 140 92UL-V rating V2 V2 V2 V2 V2 V2 Volume Resistivity (1E2 GOhm · m)^([1]) inair at 23° C. 345 166 1044 279 129 202 in water at 75° C.  1 day PassPass Pass Pass Pass Pass 7 days Pass Pass Pass Pass Pass Pass 14 days Pass Pass Pass Pass Pass Pass ^([1])The designation 1E2 GOhm · mindicates that reported values are 10⁻² times the measured value. Forexample, the reported value 126 is equivalent to a measured value of12600.

What is claimed is:
 1. A wire or cable comprising a coating made of a flame retardant polymer composition, wherein the flame retardant polymer composition comprises: a) one or more copolyetherester thermoplastic elastomers; b) melamine cyanurate; c) at least one epoxy-containing compound; and d) optionally at least one compound selected from the group consisting of phosphites and aromatic phosphate ester flame retardants and mixtures thereof; with the proviso that i) when the flame retardant polymer composition comprises an aromatic phosphate ester flame retardant and a phosphite, the amount of epoxy-containing compound present is such that the total epoxy functional group equivalent weight is at least about 32 milliequivalents per kg of the combined weight of the one or more copolyetherester thermoplastic elastomers and the aromatic phosphate ester flame retardant and ii) when the flame retardant polymer composition comprises an aromatic phosphate ester flame retardant in the absence of phosphite, the amount of epoxy-containing compound present is such that the total epoxy functional group equivalent weight is at least about 56 milliequivalents per kg of the combined weight of the one or more copolyetherester thermoplastic elastomers and the aromatic phosphate ester flame retardant.
 2. A wire or cable comprising a coating made of a flame retardant polymer composition, wherein the flame retardant polymer composition consists of: a) one or more copolyetherester thermoplastic elastomers; b) an amount of melamine cyanurate that is at least from at or equal to 10 weight percent based on the total weight of the flame retardant polymer composition; c) one or more epoxy-containing compounds; and optionally d) 0 to 2 weight percent based of the total weight of the flame retardant polymer composition of phosphite, e) 0 to 15 weight percent based on the total weight of the flame retardant polymer composition of an aromatic phosphate ester flame retardant, with the proviso that i) when the flame retardant polymer composition comprises an aromatic phosphate ester flame retardant and a phosphite, the amount of epoxy-containing compound present is such that the total epoxy functional group equivalent weight is at least about 32 milliequivalents per kg of the combined weight of the one or more copolyetherester thermoplastic elastomers and the aromatic phosphate ester flame retardant and ii) when the flame retardant polymer composition comprises an aromatic phosphate ester flame retardant in the absence of phosphite, the amount of epoxy-containing compound present is such that the total epoxy functional group equivalent weight is at least about 56 milliequivalents per kg of the combined weight of the one or more copolyetherester thermoplastic elastomers and the aromatic phosphate ester flame retardant. and f) from 0.05 to 10 weight percent based on the total weight of the flame retardant polymer composition of additives wherein the sum of component a) to f) amounts to 100 weight percent.
 3. The wire or cable according to claim 1, wherein the one or more copolyetherester thermoplastic elastomers are copolyetherester elastomers having a multiplicity of recurring long-chain ester units and short-chain ester units joined head-to-tail through ester linkages, said long-chain ester units being represented by formula (A):

and said short-chain ester units being represented by formula (B): wherein:

G is a divalent radical remaining after the removal of terminal hydroxyl groups from poly(alkylene oxide)glycols having a number average molecular weight of between about 400 and about 6000; R is a divalent radical remaining after removal of carboxyl groups from a dicarboxylic acid having a molecular weight of less than about 300; and D is a divalent radical remaining after removal of hydroxyl groups from a diol having a molecular weight less than about
 250. 4. The wire or cable according to claim 1, wherein the one or more copolyetherester thermoplastic elastomers are copolyetherester elastomers prepared from monomers comprising (1) poly(tetramethylene oxide) glycol or poly(trimethylene oxide) glycol and mixtures thereof; (2) a dicarboxylic acid selected from the group consisting of isophthalic acid, terephthalic acid and mixtures thereof; and (3) a diol selected from the group consisting of 1,4-butanediol, 1,3-propanediol and mixtures thereof.
 5. The wire or cable according to claim 1, wherein the at least one copolyetherester thermoplastic elastomers are copolyetherester elastomers prepared from monomers comprising (1) poly(tetramethylene oxide) glycol; (2) a dicarboxylic acid selected from the group consisting of terephthalic acid; and (3) a diol selected from the group consisting of 1,4-butanediol, 1,3-propanediol and mixtures thereof and wherein the level of poly(tetramethylene oxide) glycol is less than about 25 weight percent based on the total weight of the copolyetherester elastomers.
 6. The wire or cable according to claim 5, further comprising at least one copolyetherester thermoplastic elastomer prepared from monomers comprising (1) poly(tetramethylene oxide) glycol; (2) a dicarboxylic acid selected from the group consisting of mixtures of isophthalic acid and terephthalic acid; and (3) a diol selected from the group consisting of 1,4-butanediol, 1,3-propanediol and mixtures thereof and wherein the level of said copolyetherester elastomer is from about 5 to about 50 weight percent based on the total weight of the copolyetherester elastomers.
 7. The wire or cable according to claim 2, wherein the additives are selected from the group consisting of stabilizers, processing agents, metal deactivators, antioxidants, UV stabilizers, heat stabilizers, dyes and/or pigments.
 8. The wire or cable according to claim 1, wherein the amount of melamine cyanurate b) is from at or about 10 to 30 weight percent based on the total weight of the flame retardant polymer composition.
 9. The wire or cable according to claim 1, wherein the amount of epoxy-containing compound c) is such that it provides from at or about 2.4 to about 10 milliequivalents of total epoxy functionality based on hundred grams of the total weight of the flame retardant polymer composition.
 10. The wire or cable according to claim 1, wherein the amount of phosphite is from at or about 0.1 to 1 weight percent based on the total weight of the flame retardant polymer composition.
 11. The wire or cable according to claim 1, wherein the amount of aromatic phosphate ester is from at or about 2 to 12 weight percent based on the total weight of the flame retardant polymer composition.
 12. The wire or cable according to claim 1, wherein the epoxy-containing compound c) is selected from the group consisting of 2,2-bis(4-hydroxyphenyl)propane-epichlorohydrin copolymer and tetraglycidyl ether of tetraphenol ethane and combinations thereof.
 13. The wire or cable according to claim 1, wherein the phosphite is a pentaerythritol diphosphite.
 14. The wire or cable according to claim 1, wherein the aromatic phosphate ester is selected from the group consisting of resorcinol bis(di-2,6-dimethylphenyl phosphate) and bisphenol bis(di-2,6-dimethylphenyl phosphate) and combinations thereof. 